<?php
declare(strict_types=1);
function f($x,$y,){
    return 5*$x+3*$y;
}
function f2(int $x,int $y,){
    return $x+$y;
}
echo 'f(3,6)=',f(3,6),"\n";
echo 'f(3,6)=',f(1.2,2),"\n";
echo 'f2(3,6)=',f2(3,6),"\n";
echo 'f2(3,6)=',@f2((int)3.8,(int)6.6),"\n";